Green Roofs. Daniel Apt, RBF Consulting. ASCE LID Conference 2010 LID 201 Workshop

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1 Green Roofs Daniel Apt, RBF Consulting ASCE LID Conference 2010 LID 201 Workshop

2 Chicago City Hall Green Roof. Photo courtesy of Roofscapes, Inc. Green roofsare multi beneficial structural components that help to mitigate the effects of urbanization on water quality by filtering, absorbing detaining and evapotranspirating rainfall. i d t i ti i

3 Residential High Rise Solaire Residential Tower, New York. Photo courtesy of NASA Earth Observatory

4 Commercial High Rise Lincoln Mercury Headquarters, Irvine, CA. Photo courtesy of Roofscapes, Inc.

5 Commercial Building MEC Building, Toronto. Photo courtesy of Treehugger.com

6 Single Family Residential Photo courtesy of Urban Agriculture Online

7 Utility/Parks Buildings Park Building, Coraville, Iowa. Photo courtesy of NRCS

8 Building Entrance Photo courtesy of Urban Agriculture Online

9 Innovative Design Sinagapore Office Building Photo courtesy of Earth First.com

10 California Academy of Sciences i fs i Photo courtesy of Earth First.com

11 ExtensiveGreenRoof Extensive Green Roof Passive Shallow soil system Vegetation Grasses & Succulents Non recreational

12 IntensiveGreenRoof Intensive Green Roof Active Deep Soil System Vegetation Trees & Shrubs Recreational

13 Green Roof Design fd

14 Design Considerations esg sde ato s Structural Roof Support Additional weight of green roof: saturated weight pounds per square foot (extensive) pounds per square foot (intensive)

15 Design Considerations esg sde ato s Waterproof Membrane Can be various materials including: Modified asphalts (bitumens) Synthetic rubber (EPDM) Reinforced PVC Water Resistant Fabric Provides extra layer of protection t ti Synthetic oz per square yd.

16 Root Barrier Design Considerations esg sde ato s Made of dense materials that inhibit root penetration Need for a root barrier depends on the waterproof membrane used Drainage Layer Applied over the entire roof area to carry away i excess water Plastic sheets Thin layer of gravel

17 Design Considerations esg sde ato s Engineered Growing Medium/Soil Substrate Minimum of 2.5 inches thick (extensive) 3 6 inches thick (extensive) 8 24 inches thick (intensive) Well drained Typical mix of 25% topsoil, 25% compost, 50% sand but dependant on: td d t Type of plants Depth of soil Allowable weight Climate Irrigation needs

18 DesignConsiderations Design Considerations Plantings Extensive Shallow root system Good regenerative qualities Resistance to direct sunlight, drought, frost, and drought frost and wind Minimum of 90% vegetation coverage is recommended Native plants are recommended Intensive Allows for greater variety Grasses, perennials, shrubs, trees More maintenance Irrigation

19 Native Plant Pallet (Northern CA)

20 Native Plant Pallet Southern (CA)

21 Construction Concerns Waterproof membrane Protect from construction equipment punctures Inspect for leaks before other elements installed Water resistant fabric Ensure proper installation and even layout Drainage Layer Immediate inspection of drainage flows prior to soil Soil Even distribution No compaction

22 Operations & Maintenance ato s& a te a Initial Establishment Irrigation Fertilization Weeding Slow release fertilizer twice per year to l i prevent acidification of thin soil layer Maintain 90% vegetation cover Weeding Remove dead vegetation

23 Operations & Maintenance Inspect for standing water Removal of sediment that impedes dewatering Inspect roof for leaks annually Repair any damage to the waterproofing membrane, root barrier or drainage layer Irrigation Vegetation Climate General Maintenance Intensive Extensive

24 Costs Extensive: $15 to $25 per square foot Intensive: $25 to $40 & up per square foot Long term benefits and the energy savings outweigh the original investment Cost Breakdown Root Barrier/Waterproof Membrane $10 15 per sq ft Drainage Layer/Soil $5 10 per sq ft il f Plants $1 3 per sq ft Installation and labor $3 8 per sq ft Maintenance $1 2 per sq ft Irrigation system $2 4 per sq ft

25 Water Quality Metals 90 95% 95 Nitrate 75 80% Phosphate 65 70% Soil filtration Biological uptake Water Quantity Performance 60 75% of annual rainfall retention Evapotranspiration Soil retention Biological uptake

26 OtherEnvironmentalBenefits Other Environmental Benefits Energy Savings Reduction of cooling costs 50 70% Reduction of heat loss up to 25% Reduction in the Heat Island Effect Reduction of dark surfaces Plants cool through dew and evaporation cycles Improved Air Quality 1 square meter of green roof can remove 0.2 kg or airborne particulates per year Carbon dioxide reduction

27 OtherEnvironmentalBenefits Other Environmental Benefits Creation of habitat Stepping Stone habitat connecting natural isolated habitats to each other Endangered or threatened species Minimize waste by increasing roof lifespan Elimination of exposure to the sun s ultraviolet radiation i Last up to twice as long as a conventional roof Sound reduction A green roof with a 12 cm substrate can reduce sound by up to 40 decibels

28 OtherBenefits Other Benefits Aesthetics/Quality of Life Recreational Opportunities Increased Property Values Improve Employee Productivity Food Production

29 Leadership in Energy & Environmental Design (LEED) SS Credit 5.1 Protect or Restore Habitat SS Credit 5.2 Maximize Open Space SS Credit 6.1 Stormwater Design: Quantity Control SS Credit 6.1 Stormwater Design: Quality Control SS Credit 7.2 Heat Island Effect: Roof WE Credit 1.1 Water Efficient Landscaping: Reduce by 50% 1 Water Efficient Landscaping: Reduce by 50% WE Credit 1.2 Water Efficient Landscaping: No potable Water Use or No Irrigation EA Credit 1 Optimize Energy Performance ID Credit Innovation in Design

30 IssueswithGreenRoofs Issues with Green Roofs Water leakage and drainage backups Need to select appropriate waterproof membrane system Pesticide leakage Do not use pesticides Unwelcome wildlife Raccoons, squirrels, rats etc. Vegetation die off Select vegetation appropriate for climate and exposure Irrigation if necessary Irrigation requirements Select plants appropriate for conditions Some irrigation may be needed Do not over irrigate

31 GreenRoofs: Green Roofs: Lessons Learned LessonsLearned Benefits of Green Roofs must be presented early in the design process Green Roofs should be presented as cost effective over the lifecycle costs Identify the benefits (other or environmental) that target what the owner/developer values Specific to climate Installation by experienced contractor

32 Questions? Daniel Apt, RBF Consulting (949)